Dual jacketed engine provided with duplex cooling systems



July 7, 1953 D. WATKINS 3 DUAL JACKETED ENGINE PROVIDED WITH DUPLEX COOLING SYSTEMS Filed Jan. 5, 1949 Lac/u; D. MTKm/s attorneys Patented July 7, 1953 .JJHAL JACKET-ED ENGINE rPROYIDED; WITH DUI?LEX;'.COOLING:. SYSTEMS i LuciusEi D. WaItkins,'-"-Milwaukee;Wis; assignor 'to JiOutboard; Marinefit Manufacturing Company, 1Wa31kegan,lll.,w corporation ofiDelaware .Apiilication'January 5, 1949; Serial Neg-695313 I I This,JinVentiOnreIateS to adual j acketed' en- -;-'gine -provid ed wit-h duplex cooling systems in which" therespective jackets are' connected. The

- invention "has" particular :utility' in, and will be "described in' connection-with, an outboard motor; since it is -a--featureof the invention "that "different -head resistanc'es are -'establishedfor "the respective I cooling systems by discharging eoolanttherefrom' at different levels. Thus, in its *pref erred embodiment," the invention "has" par- -"ticular applicationto outboard motor practice in which the "coolant -is-"discha-rged,- instead of "being recirculated. -It is, -however, -po-ssible -to provide other" means "for varying= the *head rer'sista-ncein' the respectivesystems and, =even' in a==closed-' system; it -is' possi-ble" to diseha-rgef-the co'olant" to the -atmosphere at difierentlevels.

A'great' deal'of' study has been devoted-to the --prob1em--of cooling -an out-bard motor engine. The amount of water which is pum-ped 'through "the cooling'system at high engine speeds,- and is required to prevent overheating at such speeds, will over-cool the cylinder-- at low eng-ine' speeds, causing carbon =clepo'sits. "Outboard motors -are peculiarly subject to these problems 1 because "they are commonly used in fishing--and=are-also used'in transportation. In transportationservice, they generally operate at wide open throttle for substantial periods of timewhereas; 1 in fishing; the engine'is ordinarily operated as slowly as it will'function.

"It is further desired to supply-variable amounts of cooling wateraccording to-=the speed-of the :engine' and to' accomplish thisresult --w i thout-me- 1 chanically operative parts,- since" the heavy use' to which outboard motors are-subjected -precludes Ptheuse of anydelicatz'e parts which m-i'ght be damaged; and the failure of which 'might cause 1 expensive injury to the engine. "l 'herefor e;=coml- *pletely automatic operationwithout the =-addi- "tion'of" any moving parts is an important bbjec- -eration. ""One'of thejacketsdoes not function, at 50 all at 'low' speed operation, =--when%the heat de- -veloped is at a *min-imum, this desirably being the jacket closest'to the cylinder headwhere com- --b ustion occurs.

the drawings:

' Fig: 1. isa view partially in side elevation but '2 iarg'elyfini"vertical ioreand aft-section through an outboard motor embodying the-invention.

, 2 isaidiagrammatic View of the duplex coolingiisystem. 5 The -outheard motor Will-notbe describedin detalflpsincethe present invention-is-eoncerned *only, with the cooling-of the-cylinder block-'- 3 ;of "powerihead 5. {As .usual, the -*-power head "-is mounted, at. the upper,end-of'the-shait housing "G" which' serves as a strut connecting the" power head' with the soecalled lower unit I. Forpur- "poses of illustration, 6 I --have shown an engine having two: cylinders at= 8-and 9 with sparlc plugs at H]. T The pistons are connected "toa crank shaft: I l which drivesit-he aligned drive "shaft? I 2, "whereby epower is "communicated to 'the -pro- :peller"l3. The lower -unit l provides=- atiea'st' one-pump. illustrated, there is *a single' =pmnp chamber I4 in-iwhich there -is a cshtriugalimpeller mounted on the "vertical -"-'drive shaft 1 I 2. The

lower unit has inlets at lfi -from which the water passes through port I! into the pump casing. The"-water' =leaves-"the casing-"through a delivery port I8i located near'the periphery of-the-casing end-passes upwardly-through a conduit -'I 9 from which the separate pipes 20 and 2 I-=lead-tothe-respectivejackets 22 an'd 23.

Any de'si-red type ofjaeketrmaybe used. *For convenience of illustration, I have shown jackets which co-nst-itute *extensions of "the respective pipes, ;the extensions 2 2-and= 23 being molded -or icastidirectlyintd thercylinder'b-lock't, It-willbe 'bbservedfthatthe jaeket-=-extension 22 of p-ipeQfi passes about the-"cylinders fi and" 8'*'in=a-c1ock v wise direction, while the jacket extension zt of pjpei 2 l' passesi'aboutf thewylinders counterclock- IWiSB v As "'explainediin"therstatement" of 'obj ects, thisis' doneisothat; when-considerable'" heat is 40 'beingdeveloped at-high engine speedsp'the coldest Water; as it ariives'frorri-thapump,-cools both ofthe 'oppositej sidesof"the -'cy1inder*-b1dek alike, or nearly-so f From *thejacket extension fi of -pipe 20, there 571s a return' line 24- whi'oh= ends at ornear-wa-ter level, this being indicated by the line*meJfloe-d W." L. in bo'th =views -ofthe drawing. From the -jacket extension I 3" of pipe 2 I there is aweturn line 2 5 -'-Which ends, "preferably "in the e exhaust "conduit 26; We1i abovethe water line. The water de'li-vere'd from: pipe z 5 'passes withi':thessexhaust gases' downwardlytto: the exhaust outlet '12 When an outboar d motor is first-' started, it almost invariablyoperateslat full: speed ,xadrawing u water from the-body :ofwwatemin whichrit moves and delivering such: water :vundenipressuresofithe pump [4, l5 through the duplex cooling system to the respective jackets. There is considerably greater head resistance to the continued flow of water through the cooling system supplied by duct 21 than through the cooling system supplied by duct 20, due to the fact that the return duct 24 of the latter cooling system extends so much closer to (or below) water level, that the weight of water on the return side of the system nearly or completely balances the weight of the water in the supply side of the system so that the only energy required to maintain circulation in this system is the energy required to overcome friction therein. In the case of the system which includes supply pipe 2|, jacket 23 and return pipe 25, the head is greater because the return pipe is materially shorter than the supply pipe so that the weight of water on the return side of the system is not as great as that in the supply side, thereby creating a differential head which must constantly be overcome if water is to flow through this secondary system.

As long as the engine is operated at high speed, the pressure developed at the pump will be more than adequate to insure flow through both the primary and the secondary cooling systems. However, when the motor is throttled, as for use in trolling, the pressure developed at the pump is no longer adequate to supply both systems, and, due to the greater head in the secondary system, and the continued siphonic action in the primary system, duct will get the water in preference to duct 2! and there will be little or no flow through the jacket portions of the secondary cooling system. The jacket in the secondary cooling system is desirably located closest to the closed ends of the cylinders wherein the spark plugs are located, it being desirable to maintain a predetermined minimum temperature in the combustion chamber to avoid carbon I deposits at low speed;

I claim:

1. The combination with an engine operable at varying speeds and pump means driven therefrom at varying rates according to said engine speed, said engine being provided with a cylinder, of two separate jackets for said cylinder, primary and secondary cooling systems leading from said pump means to the respective jackets, said systems including coolant discharge pipes at differing levels, the said jackets being spaced axially of the cylinder and the jacket closest to the combustion end of said cylinder being connected in the system having its discharge at the higher level.

2. The device of claim 1 in which the respective jackets have supply and discharge connections such as to require coolant to pass circuitously about the cylinder, the said connections being reversed as between the respective systems.

3. In an outboard motor having an engine, a strut and a lower unit, portions of said outboard motor, including said lower unit, being adapted to operate submerged during the use of a motor and being provided with a water inlet. a shaft extending longitudinally of the strut, a pump in the lower unit driven by said shaft and adapted to receive water through said inlet, a

plurality of separate cooling systems supplied by said pump for cooling said engine, the engine having at least one cylinder provided with separate jackets connected into said systems, the said systems including separate return ducts leading from said jackets, one of which ducts termi-.-

. nates at a lower level than the other.

4. The device of claim 3 in which the duct which terminates at the lower level has its discharge end substantially at the level of the water in which the outboard motor operates, the discharge end of the other duct being materially above water level.

5. The device of claim 3 in which the said systems are so connected to the separate jackets that the water flows in opposite directions about said jackets.

6. The device of claim 5 in which the jacket having its discharge duct at the higher level is the jacket nearest the combustion chamber of the engine cylinder.

'7. In an outboard motor having an engine, a strut and a lower unit, portions of said outboard motor, including said lower unit, being adapted to operate submerged during the use of a motor and being providedwith a water inlet, a shaft extending longitudinally of the strut, a pump in the lower unit driven by said shaft and adapted to receive water through said inlet, a plurality of separate cooling systems supplied by said pump for cooling said engine, the engine having a plurality of cylinders'at least two of which extend horizontally, one above the other, in a common cylinder block provided with separate jackets extending about the block in substantially vertical planes spaced longitudinally of said cylinders from the heads thereof, the said jackets being connected separately into the respective systems and the said systems including separate return ducts leading from said jackets, one of which terminates at a lower level than the other whereby the system in which said other return duct is located offers a greater head resistance to flow from the pump than the system having a return duct terminating at the lower level.

8. The device of claim 7 in which the respective jackets and return ducts comprise continuously open tubes embedded in said cylinder block and extending circuitously about the respective cylinders. V

9. The device of claim 8 in which said tubes extend in opposit directionwhereby to cool both sides of the block substantially equally when both systems are in operation.

10. The device of claim 9 in which a system connected to the jacket nearest the heads of said cylinders is the system having its return duct terminating at a higher level.

11. The combination with an internal combustion engine having a cylinder, of separate primary and secondary cooling jackets for coolant therefor, and a single pump power connected to said engine and provided with branch coolant conduit connections to pass coolant to said jackets in further combination with separate coolant connection systems leading to and from the respective jackets, said connections having differing resistance to coolant flow whereby to establish a differential head resistance as between the separate systems and favor passage of coolant for one of said jackets whereby both jackets pass coolant fluid under high pump pressure but only said one jacket passes coolant fluid under low pump pressure.

12. The combination with an internal combustion engine having means for operation thereof at different speeds and having an engine cylinder provided with primary and secondary and coolant supply connections for said jackets, coolant connection for the secondary jacket being constructed to provide greater resistance to coolant flow, said coolant pump being power connected to the engine for operation at a speed to "provide coolant head in accord with the speed of operation of the engine whereby the force of coolant flow difiers respectively in said jackets at different engine speeds.

13. The combination of claim 12 in which the greater resistance to coolant flow for said secondary jacket substantially prevents coolant flow therein at predetermined minimum engine speed.

14. The combination of claim 13 wherein the connections for coolant to both jackets are of substantially equal capacity and substantially equally unobstructed, the connection for the secondary jacket having a discharge free and unobstructed at a higher level than the connection for the primary jacket whereby the head resistance of the secondary jacket and its coolant conthe primary jacket and its coolant connections and the circulation of coolant from said pump to tle primary jacket is favored at low engine spee LUCIUS D. WATKINS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,087,539 Jaenisch Feb. 17, 1914 1,306,496 Mohrdieck June 10, 1919 1,494,595 Ensslin May 20, 1924 1,500,668 Church July 8, 1924 1,567,127 Evinrude Dec. 29, 1925 1,774,881 Fry Sept. 2, 1930 1,793,713 Morrill Feb. 24, 1931 1,838,436 Morrill Dec. 29, 1931 1,979,732 Carson Nov. 6, 1934 1,985,240 Brubaker Dec. 25, 1934 2,085,810 Ljungstrom July 6, 1937 2,212,939 Irgens -1--- Aug. 27, 1940 

